During a third day of intense cross-examination, prosecutor Gerrie Nel accused the 27-year-old of having a selective memory on incriminating details of the night he killed Steenkamp in the bathroom.

The prosecutor nicknamed "the bulldog" also ripped apart the Paralympian's claim that he had rushed to the bathroom with a gun "out of instinct" that danger was lurking behind the door.

"I find your instinct strange," said Nel. "Instinct would have made sure Reeva was safe. That was never your instinct: to make sure she was safe."

Pistorius has been charged with murdering his 29-year-old model girlfriend and faces a life sentence if convicted. He has said he fired the shots accidentally and did not mean to kill anyone.

But Nel has been seeking to pick apart Pistorius's version of events.

As Nel unleashed volley after volley of questions on the details of what happened that Valentine's Day night and over apparent discrepancies in Pistorius's accounts, the sprinter grew increasingly agitated.

"I'm not looking for an excuse, if I don't remember it I don't remember it!" Pistorius said, breaking down during one exchange about the placement of objects in his bedroom.

"This is the night I lost the person I most cared about, I don't know how people don't understand that," he said through sobs.

'Why are you changing your evidence?'But Nel did not let up, accusing the double amputee sprinter of changing his version of events and of deliberately not remembering details that could be detrimental to the athlete's case.